Variable size physical sidelink control channel and aggregation

Abstract

Using a modulation and coding scheme for a control channel that is more conservative than needed to fulfill the control function may waste resources. To address this issue, a variable size control channel is provided. An apparatus in such a system may be configured to determine an aggregation level of a plurality of aggregation levels associated with a control channel. Each aggregation level of the plurality of aggregation levels is associated with a number of time-frequency resources dedicated for the control channel and a particular modulation and coding scheme used for modulating and coding control information in the control channel. The apparatus is configured to receive control information in the time-frequency resources associated with the aggregation level and decode the control information received in the time-frequency resources associated with the determined aggregation level. The decoding is based on the particular modulation and coding scheme associated with the determined aggregation level.

What is claimed is: 
     
       1. A method of wireless communication of a user equipment (UE), comprising:
 determining an aggregation level of a plurality of aggregation levels associated with a physical sidelink control channel (PSCCH), each aggregation level of the plurality of aggregation levels being associated with a number of time-frequency resources dedicated for the PSCCH and a particular modulation and coding scheme (MCS) used for modulating and coding sidelink control information (SCI) in the PSCCH; 
 receiving the SCI in the time-frequency resources associated with the aggregation level; and 
 decoding the SCI received in the time-frequency resources of the PSCCH associated with the determined aggregation level, the decoding being based on the particular MCS associated with the determined aggregation level. 
 
     
     
       2. The method of  claim 1 , wherein each aggregation level of the plurality of aggregation levels is associated with a different number of time-frequency resources dedicated for the PSCCH. 
     
     
       3. The method of  claim 1 , wherein the SCI is decoded through blind decoding by assuming different aggregation levels for the SCI, and the aggregation level is determined after receiving the SCI and after the blind decoding based on whether the SCI is successfully decoded based on the assumed aggregation level. 
     
     
       4. The method of  claim 1 , further comprising receiving a listen-before-talk (LBT) sequence before receiving the SCI in the time-frequency resources, the LBT sequence indicating the determined aggregation level, the aggregation level being determined based on the LBT sequence that indicates the aggregation level. 
     
     
       5. The method of  claim 1 , wherein demodulation reference signals (DMRS) are received within the SCI in the time-frequency resources, wherein the aggregation level is determined based on the received DMRS. 
     
     
       6. The method of  claim 5 , wherein the aggregation level is determined based on a cyclic shift of the received DMRS. 
     
     
       7. The method of  claim 1 , wherein the aggregation level is determined based on particular time-frequency resources in which the SCI is received, the particular time-frequency resources being one resource pool of a plurality of resource pools, each resource pool being associated with a corresponding aggregation level. 
     
     
       8. The method of  claim 1 , wherein the aggregation level and the associated time-frequency resources are preconfigured in the UE. 
     
     
       9. The method of  claim 1 , wherein a subset of allowed aggregation levels of the plurality of aggregation levels are preconfigured in the UE. 
     
     
       10. A method of wireless communication of a user equipment (UE), comprising:
 determining an aggregation level of a plurality of aggregation levels associated with a physical sidelink control channel (PSCCH), each aggregation level of the plurality of aggregation levels being associated with a number of time-frequency resources dedicated for the PSCCH and a particular modulation and coding scheme (MCS) used for modulating and coding sidelink control information (SCI) in the PSCCH; 
 encoding the SCI with the MCS associated with the determined aggregation level; and 
 transmitting the SCI in the time-frequency resources associated with the determined aggregation level. 
 
     
     
       11. The method of  claim 10 , wherein each aggregation level of the plurality of aggregation levels is associated with a different number of time-frequency resources dedicated for the PSCCH. 
     
     
       12. The method of  claim 10 , further comprising transmitting a listen-before-talk (LBT) sequence that indicates the determined aggregation level before transmitting the SCI in the time-frequency resources. 
     
     
       13. The method of  claim 10 , wherein demodulation reference signals (DMRS) are transmitted within the SCI in the time-frequency resources, wherein the DMRS indicates the determined aggregation level. 
     
     
       14. The method of  claim 13 , wherein a cyclic shift is applied to the DMRS, wherein the aggregation level is indicated through the cyclic shift of the DMRS. 
     
     
       15. The method of  claim 10 , wherein the time-frequency resources are invulnerable to signal-to-interference plus noise ratio (SINR) variation. 
     
     
       16. A user equipment (UE), comprising:
 a memory; and 
 at least one processor coupled to the memory and configured to:
 determine an aggregation level of a plurality of aggregation levels associated with a physical sidelink control channel (PSCCH), each aggregation level of the plurality of aggregation levels being associated with a number of time-frequency resources dedicated for the PSCCH and a particular modulation and coding scheme (MCS) used for modulating and coding sidelink control information (SCI) in the PSCCH; 
 receive the SCI in the time-frequency resources associated with the aggregation level; and 
 decode the SCI received in the time-frequency resources of the PSCCH associated with the determined aggregation level, the decoding being based on the particular MCS associated with the determined aggregation level. 
 
 
     
     
       17. The UE of  claim 16 , wherein each aggregation level of the plurality of aggregation levels is associated with a different number of time-frequency resources dedicated for the PSCCH. 
     
     
       18. The UE of  claim 16 , wherein the SCI is decoded through blind decoding by assuming different aggregation levels for the SCI, and the aggregation level is determined after receiving the SCI and after the blind decoding based on whether the SCI is successfully decoded based on the assumed aggregation level. 
     
     
       19. The UE of  claim 16 , wherein the at least one processor is further configured to receive a listen-before-talk (LBT) sequence before receiving the SCI in the time-frequency resources, the LBT sequence indicating the determined aggregation level, the aggregation level being determined based on the LBT sequence that indicates the aggregation level. 
     
     
       20. The UE of  claim 16 , wherein the at least one processor is further configured to receive demodulation reference signals (DMRS) within the received SCI in the time-frequency resources, and the aggregation level is determined based on the received DMRS. 
     
     
       21. The UE of  claim 20 , wherein the aggregation level is determined based on a cyclic shift of the received DMRS. 
     
     
       22. The UE of  claim 16 , wherein the aggregation level is determined based on particular time-frequency resources in which the SCI is received, the particular time-frequency resources being one resource pool of a plurality of resource pools, each resource pool being associated with a corresponding aggregation level. 
     
     
       23. The UE of  claim 16 , wherein the aggregation level and the associated time-frequency resources are preconfigured in the UE. 
     
     
       24. The UE of  claim 16 , wherein a subset of allowed aggregation levels of the plurality of aggregation levels are preconfigured in the UE. 
     
     
       25. A user equipment (UE), comprising:
 a memory; and 
 at least one processor coupled to the memory and configured to:
 determine an aggregation level of a plurality of aggregation levels associated with a physical sidelink control channel (PSCCH), each aggregation level of the plurality of aggregation levels being associated with a number of time-frequency resources dedicated for the PSCCH and a particular modulation and coding scheme (MCS) used for modulating and coding sidelink control information (SCI) in the PSCCH; 
 encode the SCI with the MCS associated with the determined aggregation level; and 
 transmit the SCI in the time-frequency resources associated with the determined aggregation level. 
 
 
     
     
       26. The UE of  claim 25 , wherein each aggregation level of the plurality of aggregation levels is associated with a different number of time-frequency resources dedicated for the PSCCH. 
     
     
       27. The UE of  claim 25 , wherein the at least one processor is further configured to transmit a listen-before-talk (LBT) sequence that indicates the determined aggregation level before transmitting the SCI in the time-frequency resources. 
     
     
       28. The UE of  claim 25 , wherein the at least one processor is further configured to transmit demodulation reference signals (DMRS) within the SCI in the time-frequency resources, wherein the DMRS indicates the determined aggregation level. 
     
     
       29. The UE of  claim 28 , wherein a cyclic shift is applied to the DMRS, wherein the aggregation level is indicated through the cyclic shift of the DMRS. 
     
     
       30. The UE of  claim 25 , wherein the time frequency resources are invulnerable to signal-to-interference plus noise ratio (SINK) variation.